What's the epidemic size three?

The three epidemic codes usually refer to: green code, yellow code and red team. The green code indicates that the individual is in normal health and can travel freely; The yellow code indicates that the individual has certain risks and needs to be observed and reminded; Red team said the individual was at serious risk and needed isolation and treatment. These three codes are an identification mechanism implemented in the process of epidemic prevention and control, aiming to help prevention and control personnel master personal health information, so as to carry out epidemic prevention and control work.